I. Field of the Invention
This invention relates generally to the design of an electrosurgical instrument and more particularly to an electrosurgical instrument for insertion into a laparoscopic trocar or endoscope and having one electrode which is movable relative to a stationary electrode. When the movable electrode is brought within a close predetermined distance to the fixed electrode and a voltage is applied across these electrodes, an arc is created for effecting radio frequency cutting or coagulation of a polyp or other tissue captured between the two electrodes. The device is especially adapted for trimming small polyps from the wall of the colon and, subsequently, cauterizing the remaining tissue at the site of the polyp removal. The device can also be utilized to coagulate vascular tissue areas.
II. Discussion of the Prior Art
Bipolar electrosurgical instruments typically feature a handle or housing which supports a pair of closely spaced conductive electrodes at a distal tip. These electrodes typically are stationary and extend distally from the tip and have a dielectric, such as air, therebetween. Neither is movable with respect to the other. In those electrosurgical instruments where at least one electrode is moveable, forceps-type electrodes which are movable by squeezing the electrodes toward one another, are commonly involved. In this forceps configuration, each electrode moves essentially equidistantly towards the other in one action.
U.S. Pat. No. 4,353,371, issued to Cosman, discloses a bipolar surgical instrument with longitudinally side-biting electrodes, which Is typical of the forceps-type designs. The forceps' blades are squeezed equidistantly towards one another along a longitudinal axis, as a coagulating potential is applied. Both blades of the forceps pivot towards one another within an insulating element which maintains electrical isolation at their bases. This configuration requires that the blades be placed at a right angle to the tissue to be cut if a smooth, even removal of tissue is desired.
U.S. Pat. No. 1,978,495, issued to Landau, discloses a medical instrument for the removal of tonsils. Pressure applied on a handle pushes an electrode toward a conductor. Increasing pressure eventually positions the electrode at a point where current is permitted to flow, whereupon a blade is advanced to sever the tonsil. In operation, a contact on a spring touches the conductor portion of the handle and maintains an open circuit for cutting. However, continuing pressure on the handle eventually advances the conductor forward until it is advanced to a region on the handle which is specifically dimensioned to break contact. Release of pressure on the handle permits the electrode to retreat and re-establish the circuit while the contact and handle are touching. Although exemplary of a movable electrode configuration, this device is awkward in applications other than tonsillectomies.
U.S. Pat. No. 373,399, issued to Hamilton, discloses an electrode for forming clots in varicose veins. In this device, a J-shaped rod has an electrode placed at its tip. A second electrode is placed in opposing relation on a slightly curved rod. Each electrode terminates at a conducting wire and is held within a pair of retainers. The "J"-shaped rod is held securely, but the curved rod may be displaced Proximally or distally. An adjustable stop regulates the extent of proximal or distal movement and, thus, prevents the approach of the two electrodes beyond a desired limit. After the device is positioned within body tissues, a coagulating electrical current is applied. Although this device also provides an example of a configuration for a movable electrode, this "J"-shaped rod requires greater clearance than is available in some electrosurgical applications.
It is accordingly a principal object of the present invention to provide a new and improved method and apparatus for bipolar cauterization of tissue featuring one stationary electrode and one movable electrode.
Another object of the present invention is to provide a new and improved method and electrocauterizing apparatus for encompassing polyps and the like then severing them in a guillotine fashion.
It is yet another object of the present invention to provide such a new and improved electrocauterizing apparatus dimensioned for insertion within a laparoscopic trocar or endoscope.
A further object of the present invention is to provide an electrocauterizing apparatus with a moveable electrode, further including electrocoagulating traces for coagulation of blood in the treatment region.